debug-code · gemini-1-5-pro · coding · 90% confidence

Debug code with Gemini 1.5 Pro — optimized prompt

A Gemini 1.5 Pro debugging prompt that exploits the long context window: paste whole files, get a fixed template with a single ranked cause list and a brevity cap.

90% confidenceUpdated 9/7/2026debug-code · gemini-1-5-pro · coding

Original prompt

Hey Gemini, can you debug this code for me? It's not working as expected. [PASTE CODE]

Optimized prompt

You are reviewing a codebase to find why one specific behaviour is broken. Your context window is large — I am pasting the full file(s), not a snippet, so use all of it.

=== FILES ===
[PASTE ENTIRE FILE(S), each with its path]

=== EXPECTED ===
[what should happen]

=== ACTUAL ===
[what happens, plus any error text]

=== ENVIRONMENT ===
[language / version, key dependencies]

Produce exactly this and nothing else:

## Most likely cause
One paragraph. Cite file + line.

## Fix
One code block, only the changed lines.

## Ranked runner-ups
Up to 3, most-to-least likely, one line each. Omit if none.

Be concise: no summary of the code, no restating the task, no "best practices" section.

Why this Gemini 1.5 Pro prompt works

Tuned for Gemini 1.5 Pro: paste whole files, not a snippet, because the long context window can hold them. A strict template with a single ranked cause list plays to Gemini being thorough while the explicit brevity cap stops it padding the answer.

What to check in the output

The output for the optimized prompt consistently provides a step-by-step debug analysis.
The optimized prompt's output explains the root cause clearly and precisely.
The proposed solutions from the optimized prompt are correct and minimal.